title: Age-related variation in sexual behaviours among heterosexual men residing in Brazil, Mexico and the USA.
abstract: OBJECTIVE
  To compare the prevalence of demographic characteristics and sexual behaviours across age groups and to estimate their significance in predicting sexual risk factors by age cohort.
  
  
  METHODS
  This cohort study examined sexually transmitted infection (STI) prevalence among heterosexual men in Brazil, Mexico and the USA (N=3047). Participants completed a sexual risk factor questionnaire and were tested for chlamydia, gonorrhoea, syphilis and genital herpes. We examined sexual risk in the study population through a composite measure of STI positivity by age cohort (young: 18-30 years; middle-aged: 31-44 years; older: 45-70 years). Multivariable logistic regression models were used to generate adjusted odds ratios (AORs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  We found that STI positivity varied significantly by age group among heterosexual men by a number of covariates. In younger men, having more advanced education had a protective effect (16 years: AOR=0.37, 95% CI 0.15- 0.92), whereas higher numbers of sexual partners elevated the risk for STIs (20-49 partners: AOR=2.06, 95% CI 1.04-4.06; ≥ 50 partners: AOR=4.33, 95% CI 1.74-10.76). Middle-aged men who were black (AOR=1.64, 95% CI 1.10-2.42) and divorced/separated/widowed (AOR=1.91, 95% CI 1.21-3.02) had an increased risk for a positive STI test. Among older men, a younger age at first vaginal sexual encounter (AOR=3.75, 95% CI 1.45-9.74) and a history of exchanging sex for money or drugs heightened STI risk (AOR=2.30, 95% CI 1.0-5.04).
  
  
  CONCLUSIONS
  These findings demonstrate that age-related life experiences among heterosexual men influence sexual risk and STI transmission. This topic warrants further investigation to support the development and implementation of targeted interventions that may potentially reduce adverse sexual health outcomes.
authors.affiliation: Research Coordinator, Department of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL, USA.
authors.forename: Euna M
authors.initials: EM
authors.lastname: August
authors.affiliation: Associate Professor, Department of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL, USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Daley
authors.affiliation: Professor, Department of Educational Measurement and Research, College of Education, University of South Florida, Tampa, FL, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kromrey
authors.affiliation: Professor, Department of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Baldwin
authors.affiliation: Associate Professor, Department of Anthropology, College of Arts and Sciences, University of South Florida, Tampa, FL, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Romero-Daza
authors.affiliation: Professor, Unidad de Investigación Epidemiológica en Servicios de Salud, Instituto Mexicano del Seguro Social, Cuernavaca, Morelos, México.
authors.forename: Jorge
authors.initials: J
authors.lastname: Salmeron
authors.affiliation: Director, Centro de Investigación Salud Poblacional, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lazcano-Ponce
authors.affiliation: Professor, Faculty of Medical Sciences of Santa Casa of São Paulo, São Paulo, Brazil.
authors.forename: Luisa L
authors.initials: LL
authors.lastname: Villa
authors.affiliation: Distinguished Professor, Department of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL, USA.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Bryant
authors.affiliation: Director, Center for Infection Research in Cancer, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Giuliano
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001294:Attitude to Health; D001938:Brazil / Q000453:epidemiology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D020010:Heterosexuality / Q000523:psychology* / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012725:Sexual Behavior / Q000523:psychology* / Q000706:statistics & numerical data*; D012749:Sexually Transmitted Diseases / Q000453:epidemiology*; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: HIM Study; human papillomavirus; sexual behaviour; sexually transmitted infections